Assume Melanie sees a purse siting on a park bench. She believes the purse is her friend's purse so she takes it to return it to her friend. The purse was actually placed on the park bench by the police. The police arrest Melanie for larceny. Based upon these facts alone, her best defense is
a. Entrapment
b. Mistake of Fact
c. Mistake of Law
d. Duress